Electric power steering system

Abstract

A curved leaf spring which is a first urging member surrounds an outer wheel of a second bearing, and urges, through the second bearing, a second end of a worm shaft in a direction in which the distance between the center of the worm shaft and the center of a worm wheel is shortened. A second urging member includes an annular support member received by an end surface of the outer wheel and a plurality of elastic pins extending in a direction in parallel with the axial direction of a support member. The elastic pins have fixed ends fixed to the support member and free ends that come into elastic contact with an end wall of a housing.

1. An electric power steering system which transmits power of an electric motor for assisting a steering to a steering mechanism via a transmission device that includes a drive gear and a driven gear in mesh with the drive gear, the electric power steering system comprising:
 a bearing that rotatably supports an end of the drive gear in an axial direction thereof; 
 a housing that includes a support hole for supporting the bearing in such a manner to be deviated in a direction in which a distance between an axial center of drive gear and an axial center of the driven gear varies; 
 a first urging member that elastically urges the drive gear via the bearing in a direction in which the distance between the axial centers of the drive gear and the driven gear is shortened; and 
 a second urging member that includes a plurality of elastic pins arranged in a circumferential direction of the bearing for elastically urging the bearing in the axial direction. 
 
     
     
       2. The electric power steering system according to  claim 1 , wherein the second urging member includes an annular support member, and the elastic pins have fixed ends fixed to the support member and free ends. 
     
     
       3. The electric power steering system according to  claim 2 , wherein the second urging member including the annular support member and the elastic pins is interposed between an end surface of the bearing and an opposed portion of the housing opposed to the bearing. 
     
     
       4. The electric power steering system according to  claim 3 , wherein the support member is received by the end surface of the bearing, and the free ends of the elastic pins are brought into elastic contact with the opposed portion. 
     
     
       5. The electric power steering system according to  claim 3 , wherein the support member is received by the opposed portion, and the free ends of the elastic pins are brought into elastic contact with the end surface of the bearing. 
     
     
       6. The electric power steering system according to  claim 1  further comprising a disk-shape covering member for closing an opening formed in the housing,
 wherein the elastic pins have fixed ends fixed to the covering member and free ends that come into elastic contact with the end surface of the bearing. 
 
     
     
       7. The electric power steering system according to  claim 1 , wherein the free ends of the elastic pins are of a round shape.